Installations for distributing electrical energy among a plurality of installation branches to which consumers are connected are known. The distribution is effected by way of switches designed as protective switches. Each switch has at least one switching contact which is formed from two mechanical switching elements which are adjacent to one another when the switching contact is closed. The basis for the protective function is the current flowing over the switching elements, which is detected by means of a sensor unit.
An electronic trip unit evaluates the detected current and effects a disconnection of the switching elements if a current-dependent trip condition allocated to the switch is fulfilled. In the simplest case, the trip condition consists in the exceeding of a current threshold. A mechanical switching element, e.g. in the form of a switching shaft, disconnects the switching elements if the trip condition is satisfied and the trip unit has generated a corresponding trip signal.
The disadvantage here is that the switches in the switching installation are usually installed in switch cabinets, wherein their display elements are not visible as displays when the cabinet door is closed. It is not therefore possible to read out the parameters of the switches without additional effort. The same applies to the parameters measured by the switches, such as the load currents and voltages of the individual phases, and also the performance data.
One solution for overcoming these disadvantages consists in providing corresponding recesses or openings in the switch cabinet door and in arranging the switch or switches in such a way that the display elements are visible from outside.
A different solution uses a remote external display for each switch, said display being connected via a communication link to the associated switch only. These displays are fitted outside the switch cabinet, e.g. on the switch cabinet door. In this solution, a dedicated display is managed for each switch.